一种宽共模输入范围的高速CAN总线接收器设计

Design of a high speed CAN bus receiver with a wide common-mode input range

为保证24 V供电的汽车电子系统在复杂环境下可靠通信,同时满足CAN FD总线协议高速率的要求,设计了一种宽共模输入范围的高速CAN总线接收器。采用三级放大结构实现,输入级预放大电路通过共模位移与共射极相结合的方法,扩大共模电压输入范围;增益级为输出限幅的折叠式差分放大结构,提升接收器的速度和增益;输出级利用反相器放大级,实现模拟信号到数字信号的高速转换。基于0.18μm 60 V BCD工艺完成设计与流片,测试结果表明,5 V电源电压下,接收器阈值电压的温漂系数在-40~150℃范围内为75×10^(-6)/℃,共模电压输入范围为±30 V,传输延迟小于58 ns。

A high speed CAN(Controller Area Network)bus receiver was designed with wide common mode input range to ensure reliable communication in automotive electronic system at 24 V power supply in complex environment and to meet the requirement of high speed of CAN FD(CAN with Flexible Data rate)bus protocol.Three-stage amplifier structure was adopted.The input stage pre-amplifier enlarges the input voltage range by combining common-mode shift with commonemitter.The gain stage is a folded differential amplifier with output limiting,which increases the speed and gain.Finally,the output stage uses the inverter amplification to realize high-speed conversion from analog to digital signal.The proposed CAN bus receiver was designed and then fabricated using a 0.18μm 60 V BCD(Bipolar-CMOS-DMOS)process.Test results show that at 5 V supply voltage the temperature drift coefficient of the receiver threshold voltage is 75×10^(-6)/℃from-40 to 150℃.Common mode voltage input range is±30 V,and the transmission delay is less than 58 ns.